$-4qr - 9qs - 10q + 5 = -r - 2$ Solve for $q$.
Answer: Combine constant terms on the right. $-4qr - 9qs - 10q + {5} = -r - {2}$ $-4qr - 9qs - 10q = -r - {7}$ Notice that all the terms on the left-hand side of the equation have $q$ in them. $-4{q}r - 9{q}s - 10{q} = -r - 7$ Factor out the $q$ ${q} \cdot \left( -4r - 9s - 10 \right) = -r - 7$ Isolate the $q$ $q \cdot \left( -{4r - 9s - 10} \right) = -r - 7$ $q = \dfrac{ -r - 7 }{ -{4r - 9s - 10} }$ We can simplify this by multiplying the top and bottom by $-1$. $q= \dfrac{r + 7}{4r + 9s + 10}$